Recent sediments, sediment accumulation and carbon burial at Goban Spur, NW European Continental Margin (47-50 degrees N)

To quantify recent sediment accumulation, carbon fluxes and cycling, three N.W. European Continental Margin transects on Goban Spur and Meriadzek Terr ace were extensively studied by repeated box- and multicore sampling of bot tom sediments. The recent sediment distribution and characteristics appear directly related to the near-bed hydrodynamic regime on the margin, which a t the upper slope break on the Goban Spur results in along-slope and period ic off-slope directed transport of particles, possibly by entrainment of pa rticles in a detached bottom or intermediate nepheloid layer. From the shel f to the abyssal plain the surface sediments on the Goban Spur change from terrigenous sandy shelf sediments into clayey silts. Pb-210 activity decrea ses exponentially down core, reaching a stable background value at 10 cm (s hallower stations) to 5 cm (deeper stations) sediment depth. Pb-210 profile s of repeatedly sampled stations indicate negligible annual variability of mixing and flux. The Pb-210, flux to the sediment shows a decreasing trend with increasing water depth. Below about 2000 m the average Pb-210(xs) flux is about 0.3 dpm cm(-2) y(-1), a third of the fluxes measured on the shelf and upper slope stations. Sediment mixing rates (D-b) correlate with macro - and meiofaunal density changes and are within the normal oceanic ranges. Lower mixing rates on the lower slope likely reflect lower organic carbon f luxes there. Mass accumulation rates on Meriadzek Terrace are at maximum 80 g m(-2) y(-1), almost twice as high as at Goban Spur stations of comparabl e depth. A minimum accumulation rate of 16.6 g m(-2) y(-1) is found at the Goban Spur upper slope break. Organic carbon burial rates are low compared to other margins and range from a lowest value of 0.05 g m(-2) y(-1) at the upper slope break to 0.11 g m(-2) y(-1) downslope. A maximum organic carbo n burial rate of 0.41 g m(-2) y(-1) is found on Meriadzek Terrace. Carbonat e burial rates increase along the northern transect from the shelf (13 g m( -2) y(-1)) via a low (9.3 g m(-2) y(-1)) on the upper slope break to the de ep sea (30.7 g m(-2) y(-1)). Carbonate burial is highest on Meriadzek Terra ce (44.5 g m(-2) y(-1)). The N.W. European Margin at Goban Spur and Meriadz ek Terrace cannot be considered a major carbon depocenter. (C) 1998 Elsevie r Science Ltd. All rights reserved.